pH和NaCl浓度对核桃蛋白纳米颗粒 Pickering乳液稳定性的影响Effect of pH and NaCl concentration on stability of Pickering emulsion stabilized with walnut protein nanoparticles

Abstract

为提高核桃蛋白Pickering乳液的稳定性，以核桃蛋白纳米颗粒（Nano-WPI）为稳定剂制备Pickering乳液，分析不同pH（2.0～8.0）和NaCl浓度（0～400 mmol/L）对Pickering乳液乳化活性、粒径、流变特性、热稳定性和贮藏稳定性的影响。结果表明：Pickering乳液稳定性随pH增加先降低后升高；pH为8.0时，Pickering乳液乳化活性最大（32.79 m2/g），平均粒径为3.33 μm，乳液呈弱凝胶特性，热稳定性和贮藏稳定性良好，综合性能最佳；随NaCl浓度增加，Pickering乳液乳化活性先减小后增大，粒径先增大后减小，NaCl浓度与表观黏度、储能模量和贮藏稳定性呈正相关；NaCl浓度为400 mmol/L时，Pickering乳液乳化活性为13.18 m2/g，平均粒径为9.28 μm，乳液呈凝胶特性，贮藏稳定性良好，但热稳定性降低，综合性能较优。综上，pH远离Nano-WPI等电点（4.0～50）或增加NaCl浓度可提高Pickering乳液的综合性能。To improve the stability of the walnut protein Pickering emulsion, the Pickering emulsion was prepared using walnut protein nanoparticles (Nano-WPI) as stabilizers, and the effects of pH (2.0-8.0) and NaCl concentration (0-400 mmol/L) on the emulsification activity (EAI), particle size, rheological properties, thermal stability, and storage stability of the Pickering emulsion were analyzed. The results showed that the stability of the Pickering emulsion first decreased and then increased with the increase of pH. At pH 8.0, the Pickering emulsion had the highest EAI (32.79 m2/g) with an average particle size of 3.33 μm, and showed weak gel characteristics with good thermal and storage stability. At pH 8.0, the comprehensive property of the Pickering emulsion was the best. With the increase of NaCl concentration, the EAI of the Pickering emulsion decreased and then increased, while the particle size of the Pickering emulsion was the opposite. NaCl concentration positively correlated with the apparent viscosity, storage modulus, and storage stability of the Pickering emulsion. When the NaCl concentration was 400 mmol/L, the EAI of Pickering emulsion was 1318 m2/g with an average particle size of 9.28 μm, and the Pickering emulsion showed gel characteristics with good storage stability but low thermal stability. When the NaCl concentration was 400 mmol/L, the comprehensive property of the Pickering emulsion was the best. In conclusion, if the pH is far away from the isoelectric point (4.0-5.0) of Nano-WPI or NaCl concentration increases, the comprehensive property of the Pickering emulsion can be improved.

Keywords

• 核桃蛋白纳米颗粒；pickering乳液；ph；nacl浓度；稳定性
• walnut protein nanoparticles; pickering emulsion; ph; nacl concentration; stability